öljykylpykytkin

An oil-immersed switch, or "öljykylpykytkin" in Finnish, is a type of electrical switch that is submerged in oil. This oil serves multiple purposes, primarily as an insulator and a cooling medium. When an electrical circuit is broken, an arc forms between the switch contacts. The oil surrounding the contacts helps to extinguish this arc by cooling and deionizing the area. This arc suppression is crucial for preventing damage to the switch and the electrical system.

These switches are commonly used in high-voltage applications, such as in power distribution systems and substations. Their robust construction and effective arc-quenching capabilities make them suitable for interrupting large electrical currents. The oil also provides a barrier against atmospheric contaminants like dust and moisture, which can degrade the performance of dry-type switches.

Maintenance of oil-immersed switches involves periodically checking the oil level and quality. Over time, the oil can degrade due to repeated arc quenching and exposure to heat, leading to a decrease in its insulating properties. This can necessitate oil filtration or replacement. Despite the need for maintenance, oil-immersed switches have a long service life and are a reliable choice for many heavy-duty electrical switching applications. They are known for their ability to handle significant fault currents.